Glycosylation of phytepsin and expression of dad1, dad2 and ost1 during onset of cell death in germinating barley scutella

Dysfunction and downregulation of clad (defending against death) has bean l inked to programmed cell death (PCD) in animals and plants. As DAD is an es sential subunit of the oligosaccharyltransferase that is located in the ER membrane, the results have raised the possibility that downregulation of N- linked glycosylation could be involved in the regulation of PCD. Here we sh ow that the 16 kDa subunit of phytepsin, a vacuolar proteinase, is normally processed and glycosylated at the onset of DNA fragmentation in germinatin g barley scutella. Two cDNA clones encoding dad (dad1, dad2), and one cDNA encoding another subunit of the same oligosaccharyltransferase complex (ost i1) were isolated from barley. Northern analysis of germinating scutella sh ow that the expression of only dad1 is declining before onset of DNA fragme ntation. In contrast to this, the expression of both dad2 and ost1 increase before onset of DNA fragmentation. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.